This invention relates to aerosol dispensers and, more particularly, to such dispensers wherein a liquid spray is discharged from the dispenser by a propellant gas when a valve on the aerosol dispenser is actuated.
Aerosol dispensers are utilized for packaging and dispensing a wide variety of liquids. When the dispensing valve is actuated by depressing the stem of the valve extending outwardly from the top of the dispenser, the liquid is sprayed out of the dispenser through an orifice in the valve stem. The liquid is discharged through and out of the orifice in a spray pattern.
With some materials such as quick drying hair sprays, the uniformity of the spray pattern and the size of the liquid particles in the pattern sprayed are of particular importance. Variation in the pattern and variations in the size of the liquid particles during the time when the contents of the dispenser are being used can adversely effect the spray application of the liquid and the effectiveness of such liquid.
Various attempts have been made to improve the spray pattern and uniformity of the particle size of the liquid sprayed from aerosol dispensers. Such attempts have included arrangements in the valves, the orifices, and the internal diameter of the dip tube.
Exemplary methods for converting liquid into fine spray are those disclosed in U.S. Pat. No. 3,421,692 and U.S. Pat. No. 3,421,699, which are hereby incorporated by reference. In these patents, liquid is introduced onto a smooth surface having an aperture therethrough which causes the liquid to "film out" on the surface either by surface tension or by the shape of the surface so that the liquid is under stress before it reaches the aperture. The film flows over the aperture through which a gaseous dispensing medium is discharged to create minuscle particles of the thin liquid film to form a fine particle spray.